“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

A woman sits in a cell at the Los Angeles County Women's jail in Lynwood, California April 26, 2013. (Photo by Lucy Nicholson/Reuters)

Members of Team Italy are seen underwater as they perform in the synchronised swimming team free routine preliminary at the Aquatics World Championships in Kazan, Russia July 28, 2015. (Photo by Michael Dalder/Reuters)

An indigenous girl carries a monkey inside her house in their village at Xingu national park in Mato Grosso, Brazil, October 2, 2015. The Kamayura tribe consists of around 300 people, and is one of the 16 ethnic groups living in the indigenous Xingu national park. (Photo by Paulo Whitaker/Reuters)

Tribal artists and supporters from the southern Indian state of Karnataka dance outside the residence of Congress Party President Sonia Gandhi during her birthday celebrations in New Delhi, India, Wednesday, December 9, 2015. The Italian-born Gandhi is the widow of former Prime Minister Rajiv Gandhi and has led the Congress party since 1998. (Photo by Altaf Qadri/AP Photo)

Participants of the 77th edition of the annual Christmas swimming 'Coupe de Noel' jump into the waters of Lake Geneva, in Geneva, Switzerland, 20 December 2015. More than 1,540 men and women braved the water temperature of just 8 degrees Celsius as they swam a 120 meters distance at the traditional Christmas swimming in Geneva. (Photo by Salvatore Di Nolfi/EPA)

Lightning strikes during a storm over the Ionian Sea in Calabria, Italy on June 27, 2016. (Photo by Alfonso Di Vincenzo/Pacific Press/Rex Features)

Students walk to school on the first day of their new school year in Giza, south of Cairo, Egypt September 25, 2016. (Photo by Mohamed Abd El Ghany/Reuters)